Hamming Code

Problem:

http://ace.delos.com/usacoprob2?a=GDaP3qeGiYp&S=hamming

My Answer:

/*
ID:iby071
LANG:C++
TASK:hamming
*/

#include<iostream>
#include<fstream>
using namespace std;

int n,b,d;

int hamming(unsigned long int x,long int y)		
{	unsigned long int tmp=x^y,cnt=0;			//^：异或
	for(int i=0;i<b;++i)
		cnt+=(tmp>>i)&1;			//取从右往左第i+1位
	return cnt;
}

int main()
{	ifstream fin("hamming.in");
	ofstream fout("hamming.out");
	int cnt=0,j;
	unsigned long int a[65];

	fin>>n>>b>>d;

	a[0]=0;
	++cnt;

	for(unsigned long int i=1;i<(1<<b);++i)			//1<<b即2的b次方
	{	for(j=0;j<cnt;++j)
			if(hamming(i,a[j])<d) break;
		if(j==cnt) {a[cnt]=i;++cnt;}
		if(cnt==n) break;
	}
	

	fout<<a[0];
	for(int i=1;i<n;++i)
	{	if(i%10==0) fout<<endl;				//注意：要求输出为10个一行
		else fout<<' ';
		fout<<a[i];
	}
	fout<<endl;
	
	return 0;
}